The present invention relates to the general technical field of manufacturing tanks for cryogenic fluids.
The subject of the invention is, more specifically, tanks for cryogenic fluid, insulated by the technique called super insulation.
In the prior art, it is known to use cryogenic fluid tanks, in this instance for liquefied gases such as liquid hydrogen or liquid helium. Such a tank comprises an inner vessel equipped with pipes for filling and extracting the cryogenic fluid. This inner vessel is covered on the outside with high-performance thermal insulation in order to prevent the stored fluid evaporating too quickly. This vessel is thus insulated by the technique called super insulation, which aims to put in place multilayer thermal insulation consisting of the superposition of a heat reflector and of a thermally insulating interlayer. Conventionally, this multilayer thermal insulation is produced by means of winding at least one insulating strip consisting, in particular, of the superposition of a thin aluminium sheet forming a reflector and of an insulating paper or glass fibre sheet forming the interlayer. The insulating strip is wound using an insulating machine which winds the strip around the vessel, while the latter is set in rotation about its axis.
The tank also comprises an outer protective vessel intended to surround the multilayer thermal insulation. This outer vessel, which is generally made in two parts, is fastened to the inner vessel via connecting supports of the tie-rod or centring-feet type, passing through the multilayer thermal insulation. In practice, putting the supports in place on the vessels and fastening the vessels together are operations which are expensive and tricky to carry out properly.
Also, there appears to be a need to have available a technique for manufacturing a tank for a cryogenic fluid, adapted to be simple, cheap and capable of being carried out automatically, while making it possible to put in place high-performance thermal insulation which does not lead to an increase in the size of the tank for a given storage volume of the cryogenic fluid.
The object of the invention is therefore aimed at satisfying this need by providing a method for manufacturing a tank intended to contain a cryogenic fluid, the method being adapted to be simple, capable of being carried out automatically and cheap, while at the same time making it possible to obtain high-performance thermal insulation having a limited size in order to obtain a light, cheap and high-performance tank, especially for use in land or air vehicles.
The subject of the invention is therefore a method of manufacturing a tank intended to contain a cryogenic fluid, the method consisting in fitting an inner vessel intended to receive the cryogenic fluid, inside an outer protective vessel which delimits, with the inner vessel, a space for the insertion of multilayer thermal insulation.
According to the invention, the method consists in:
fitting the multilayer thermal insulation around the inner vessel, such that the said thermal insulation supports the inner vessel, and
fitting the outer vessel around the multilayer thermal insulation, without a rigid connection to the inner vessel.
The subject of the invention is also a tank for cryogenic fluid, of the type comprising an inner vessel intended to receive the cryogenic fluid and which delimits, with an outer vessel, a space for the insertion of multilayer thermal insulation. According to the invention, the reservoir comprises multilayer thermal insulation supporting, on its own, via insulating interlayers, the inner vessel and an outer vessel without a rigid connection to the inner vessel.
Another subject of the invention relates to an insulating machine for implementing the method of manufacturing a tank for cryogenic fluid, the machine comprising means to set in rotation, about its axis, an inner vessel for cryogenic fluid and means to wind around the inner vessel, an insulating strip forming several superimposed insulating layers, each one consisting of a thermally insulating interlayer and of a heat reflector.
According to the invention, the machine comprises means to wind, at least locally about the inner vessel, at least one series of thermal insulation strips inserted in a superimposed manner between the heat reflectors in order to support the inner vessel and to separate the heat reflectors.